The present invention relates to an all-purpose AC ballast applicable for use in tungsten filament lamp tubes. The ballast is capable of instantaneously turning on the lamp tube even if the tungsten of the lamp tube is severed, and is also capable of adjustment for light intensity.
Conventional ballasts for fluorescent lamps normally include a binary alloy and neon or argon gases. Cold cathode discharge is accomplished by heating the binary alloy to cause a stabilizer to produce high voltage to turn on the tube. In recent years, the alternative technology of using DC powered ballasts to produce high frequency oscillating voltages has become prevelant.
However, while enabling instantaneous starts, electronic ballasts provide little improvement in the durability of the lamp tube. Using this technology, when the tungsten filament is cut-off, the lamp becomes inoperable. Also, such starters do not provide optimum energy efficiency and are therefore relatively expensive to operate. Finally, presently used fluorescent lamps do not permit adjustment of current or light intensity.
Such disadvantages cause consumers to install neon or electric lamps rather than fluorescent lamps for such purposes as advertising illumination because of the long-term and heavy expenditure on electricity resulting from inefficient ballasts.
The present invention overcomes these drawbacks and problems by providing an all-purpose electronic ballast which elicits better performance from tungsten lamp tubes, even when one of the tungsten filaments is missing or broken.